Customer-
what is the difference between LC 51 and LC 1000 ink cartridge?
Dimmusacio-
They are used with different types of ink delivery systems. The LC-51 cartridges will not work in a machine that uses LC-1000 cartridges and vice versa. They also have a slightly different shape. Your MFC 465CN for example will not work with LC-51 ink cartridges.
